The propellers hub/blade assembly (see figure 4-6), attached to the main propulsion propeller shaft, provides the mounting for the propeller blades and houses the blade turning mechanism for rotating and holding the pitch position of the blades. Attached to the after end of the hub body are the hub cone and the hub cone end cover. These items form the chamber for the servomotor piston. The hub body is fitted to the tailshaft by guide pin dowels which also transmit the torque

Table 4-2.CRP Propeller Hardware Components

from the shafting to the hub assembly. The hub is secured to the tailshaft by flange bolts. These bolts are not designed to take torque from the tail shaft. The hub to tailshaft joint is sealed by O-rings located between the hub and the tailshaft, and between the tailshaft and the tailshaft spigot. Each blade is attached to a crank pin ring by blade bolts. The crank pin ring fits over and rotates about a center post which is physically a part of the hub body. The crank pin ring is retained in the hub by the bearing ring. The area under each blade is sealed by the blade port cover and by two O-rings in the blade seal base ring. Each blade seal base ring is spring-loaded against the under-side of the blade port cover to provide a sealing surface under all loading conditions. The blade turning mechanism in the hub con-sists of a single crosshead, attached to the end of a piston rod. Several sliding blocks are fitted into the machined chambers of the crosshead. An eccentric pin on the underside of each crank pin ring fits into a hole machined into each sliding block. The hub servomotor is attached to the after end of the crosshead. A piston rod carries the lines for the regulating valve pin which is attached to the end of the valve rod. This assembly forms a passage for hydraulic power oil flow and return oil flow to and from the hub.